The anterior abdominal wall provides core support to the human torso, confines abdominal viscera, and contributes muscular action for functions such as respiration and elimination. In gynecology, an understanding of the layered structure of the anterior abdominal wall is needed to effectively enter the peritoneal cavity for surgery without neurovascular complications.
Skin and Subcutaneous Layer
Within the skin, the term Langer lines describes the orientation of dermal fibers. In the anterior abdominal wall, they are arranged primarily transversely (Fig. 38-1). As a result, vertical skin incisions sustain more lateral tension and thus in general, develop wider scars compared with transverse skin incisions.
Langer lines of skin tension.
The subcutaneous layer lies deep to the skin. In the anterior abdominal wall, this layer is separated into a superficial, predominantly fatty layer known as Camper fascia and a deeper, more membranous layer known as Scarpa fascia (Fig. 38-2). Camper and Scarpa fasciae are not discrete layers but represent a continuum. If traced caudally, scarpa fascia is continuous with Colles fascia in the perineum.
Transverse sections of the anterior abdominal wall above (A) and below (B) the arcuate line.
Clinically, Scarpa fascia is better developed in the lower abdomen and during surgery can be best identified in the lateral portions of a low transverse incision, just superficial to the rectus fascia. In contrast, this fascia is rarely recognized during midline incisions.
The external oblique, internal oblique, and transversus abdominis muscles (flank muscles) all contain a lateral muscular portion and medial fibrous aponeurotic portion. All of their aponeuroses conjoin, and these layers create the rectus sheath (see Fig. 38-2). In the midline, the aponeurotic layers fuse to create the linea alba. In the lower abdomen, transition from the muscular to the aponeurotic component of the external oblique muscle takes place along a vertical line through the anterior superior iliac spine. Transition from muscle to aponeurosis for the internal oblique and transversus abdominis muscles takes place at a more medial site. Accordingly, during low transverse incisions, muscle fibers of the internal oblique muscle are often noted below the aponeurotic layer of the external oblique muscle.
The anatomy of the rectus sheath above and below the arcuate line has significance (see Fig. 38-2). This horizontal line defines the level at which the rectus sheath passes only anterior to the rectus abdominis muscle, and this line typically lies midway between the umbilicus and pubic symphysis. Cephalad to the arcuate line, the rectus sheath lies both anterior and posterior to the rectus abdominis muscle. At this level, the anterior rectus sheath is ...